Long non-coding RNA KCNQ1OT1 increases the expression of PDCD4 by targeting miR-181a-5p, contributing to cardiomyocyte apoptosis in diabetic cardiomyopathy

Aims Diabetic cardiomyopathy (DCM) is a specific myocardial alteration in patients with diabetics. LncRNA KCNQ1OT1 has been previously demonstrated to be involved in various diabetic complications. Our aims are to further investigate the underlying regulatory mechanisms/pathways of KCNQ1OT1 in DCM. Methods In vitro and in vivo models of DCM were established in high glucose (HG)-treated human cardiomyocytes and in streptozotocin (STZ)-induced diabetic mice, respectively. Gene and protein expressions were examined by qPCR, western blotting and ELISA. Cell proliferation and apoptosis were determined by CCK8 assay, flow cytometry and TUNEL staining. The association between KCNQ1OT1 and miR-181a-5p, miR-181a-5p and PDCD4 was predicted using bioinformatics methods and subsequently confirmed by dual luciferase reporter and RNA immunoprecipitation assays. Mouse cardiac tissues were collected and analysed using HE staining, Masson’s staining and immunohistochemical analysis. Results KCNQ1OT1 and PDCD4 were upregulated in HG-treated human cardiomyocytes, while miR-181a-5p was downregulated. In addition, KCNQ1OT1 could negatively regulate miR-181a-5p expression; meanwhile, miR-181a-5p also negatively regulated PDCD4 expression. KCNQ1OT1 silencing suppressed the expression of inflammatory cytokines and cell apoptosis in vitro, whereas inhibition of miR-181a-5p abrogated those effects of KCNQ1OT1 knockdown. Moreover, overexpressed PDCD4 abolished the inhibition on inflammation and apoptosis caused by miR-181a-5p overexpression. Finally, KCNQ1OT1 knockdown reduced the expression of PDCD4 via regulating miR-181a-5p and inhibited myocardial inflammation and cardiomyocyte apoptosis in the in vivo DCM model. Conclusions Our findings suggest that KCNQ1OT1 and its target gene miR-181a-5p regulate myocardial inflammation and cardiomyocyte apoptosis by modulating PDCD4 in DCM.